Hell, you could change absolutely nothing and just call them Orcs and people would accept it.
People have been offended by orcs for close to a hundred years now. It's called subtext.
Hell, you could change absolutely nothing and just call them Orcs and people would accept it.
Readers are stupid. They'll see things you never intended.
Will people be offended by primative, tribal black humans? Yes. I like to think we're all genre savy enough to accept that.
If you want people to not be offended, then you're going to have to change that mental image of them. You can do this through how you portray them, but the simplest way is to change how they look. People are a lot more willing to accept things that might be stereotypical at first glance, regardless of whether it's actually stereotypical or not, if their portrayed as not human.
I maintain, vagueness is your friend. Provide only what you absolutely must, and let the reader's immagination fill in the rest.
People are offended by the smurfs...
In my opinion, I think it's always best to defer to a large group of people who say they are being offended. To do otherwise is a bit like telling someone they don't feel a certain way.
You can acknowledge that people might feel a certain way, but that doesn't mean you have to agree with their feelings or cater to them.
I'm trying to think of what bothered me when I first saw the pictures. It may be the style. I don't mean to offend your sensibilites, but perhaps a more realistic style of drawing instead of a cartoonish one would read differently. It might be part of why people don't take it seriously.
Straighten the hair. Make it long maybe make it red. You know, add an atypical element to the design and it may not seem as blatant to the reader.